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Quick Takes - SEEC HQSN-4U AC Line Filter - July, 2001

Milan Cernohorsky




SEEC HQSN-4U AC Line Filter


Compact module with hyperactive filtration circuit
Triple coil for the elimination of RF and EMI disturbances
Use of high-quality cable
Automatic protection from discharges and voltage peaks
Anti-fire protection - 1100C limit point
Optional length of the power-supply cable according to the customer's wish
Power indicator
Three-year guarantee
Filter nominal load is 850 Watt, for the American export version 550 Watt
Size: 123mm x 70mm x 30mm
MSRP: $350

When I came across the Dutch company SEEC Int. on the Internet about two months ago, my attention was particularly drawn to two products, the HQSN-4U network filter and ASC-2 active cable (the latter reminded me of the Dudek's SR).

The company is based in the city of Mierlo in the Brabant region, close to the Belgian border. Kees van Haaren is its founder and chief designer. SEEC Int., founded in 1988, mainly deals with the production of audio products for professional and semi-professional applications. Besides the the above-mentioned network filter and active cables, they make preamplifiers and power amplifiers.

After a relatively short exchange of correspondence with Mr. Haaren, both the above-mentioned products arrived to Prague (the active cable is covered in a separate review), carefully wrapped and accompanied with excellent support materials.

So far SEEC Int. offers two models of filters - the HQSN-4U and the HQSN-4UL. Other types are being developed. The task of the AC filter is to improve the electrical supply coming from our walls. The advantage of this Dutch model is that it protects audio and video components from damages caused by voltage peaks (surge protection).

The use of such filters is supposed to improve the dynamics and details at low volume level. They can be used for all audio/video products. The SEEC unit has coils (inductors) but no transformers. The AC cable is permanently mounted to the filter box, with one output socket (for connection with a multi-socket extension cord. A red LED signal indicates proper functioning.

I connected the filter directly to the wall and then I connected an extension cable by the HAMA company with four sockets to it. In the past I exchanged the thin input network cable for a solid-core type. The input part was cut down to the minimum so that this "antenna" would be as short as possible. Approximately half an hour before the listening I warmed up the components including the SEEC AC filter.

The first thing that I immediately noticed during music reproduction was a refining of highs (diminishing of the legendary digital grain). Cymbals in the recording of Scott Henderson sounded finer and more natural. Subjective impressions were that the volume was up a bit. I previously noticed that with my first (and by the way very successful) AC filter by Czech producer, OkTechnik. Mid and upper bass is firmer and better defined. I noticed similar effect with the use of the active SR cables by Pavel Dudek (Czech producer). Spaciousness is also opened up.

My conclusion on this is that the HQSN-4U functions as advertised and is worth the investment.


Ease of Use:

- Milan Cernohorsky -


Copyright 2001 Secrets of Home Theater & High Fidelity

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